A1 Journal article (refereed)
Disentangling the Effect of Pressure and Mixing on a Mechanochemical Bromination Reaction by Solid‐state NMR Spectroscopy (2023)

Bartalucci, E., Schumacher, C., Hendrickx, L., Puccetti, F., d'Anciães Almeida Silva, I., Dervişoğlu, R., Puttreddy, R., Bolm, C., & Wiegand, T. (2023). Disentangling the Effect of Pressure and Mixing on a Mechanochemical Bromination Reaction by Solid‐state NMR Spectroscopy. Chemistry : A European Journal , 29(12), Article e202203466. https://doi.org/10.1002/chem.202203466

JYU authors or editors

Publication details

All authors or editors: Bartalucci, Ettore; Schumacher, Christian; Hendrickx, Leeroy; Puccetti, Francesco; d'Anciães Almeida Silva, Igor; Dervişoğlu, Rıza; Puttreddy, Rakesh; Bolm, Carsten; Wiegand, Thomas

Journal or series: Chemistry : A European Journal

ISSN: 0947-6539

eISSN: 1521-3765

Publication year: 2023

Publication date: 29/11/2022

Volume: 29

Issue number: 12

Article number: e202203466

Publisher: Wiley-VCH Verlag

Publication country: Germany

Publication language: English

DOI: https://doi.org/10.1002/chem.202203466

Publication open access: Openly available

Publication channel open access: Partially open access channel

Web address of parallel published publication (pre-print): https://chemrxiv.org/engage/chemrxiv/article-details/635bc2491db0bd95c13d5dbd

Abstract

Mechanical forces, including compressive stresses, have a significant impact on chemical reactions. Besides the preparative opportunities, mechanochemical conditions benefit from the absence of any organic solvent, the possibility of a significant synthetic acceleration and unique reaction pathways. Together with an accurate characterization of ball-milling products, the development of a deeper mechanistic understanding of the occurring transformations at a molecular level is critical for fully grasping the potential of organic mechanosynthesis. We herein studied a bromination of a cyclic sulfoximine in a mixer mill and used solid-state nuclear magnetic resonance (NMR) spectroscopy for structural characterization of the reaction products. Magic-angle spinning (MAS) was applied for elucidating the product mixtures taken from the milling jar without introducing any further post-processing on the sample. Ex-situ 13C-detected NMR spectra of ball-milling products showed the formation of a rather crystalline solid phase with the regioselective bromination of the S-aryl group of the heterocycle in position 4. Completion is reached in less than 30 minutes as deduced from the NMR spectra. The bromination can also be achieved by magnetic stirring, but then, a longer reaction time is required. Mixing the solid educts in the NMR rotor allows to get in-situ insights into the reaction and enables the detection of a reaction intermediate. The pressure alone induced in the rotor by MAS is not sufficient to lead to full conversion and the reaction occurs on slower time scales than in the ball mill, which is crucial for analysing mixtures taken from the milling jar by solid-state NMR. Our data suggest that on top of centrifugal forces, an efficient mixing of the starting materials is required for reaching a complete reaction.

Keywords: NMR spectroscopy

Free keywords: ball milling; high-pressure chemistry; mechanochemistry; mixing; NMR spectroscopy

Contributing organizations

Ministry reporting: Yes

Reporting Year: 2023

JUFO rating: 2